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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 127 records · Page 7
All sourcesNASA NTRSDOE OSTI
NASA NTRS1986

Characterization of nucleoside triphosphatase activity in isolated pea nuclei and its photoreversible regulation by light

A nucleoside triphosphatase (NTPase) present in highly purified preparations of pea nuclei was partially characterized. The activity of this enzyme was stimulated by divalent cations (Mg2+ = Mn2+ > Ca2+), but was not affected by the monovalent cations, Na+ and K+. The Mg(2+)-dependent activity was further stimulated by concentrations of Ca2+ in the low micromolar range. It could catalyze the hydrolysis of ATP, GTP, UTP, and CTP, all with a pH optimum of 7.5. The nuclear NTPase activity was not inhibited by vanadate, oligomycin, or nitrate, but was inhibited by relatively low concentrations of quercetin and the calmodulin inhibitor, compound 48/80. The NTPase was stimulated more than 50% by red light, and this effect was reversed by subsequent irradiation with far-red light. The photoreversibility of the stimulation indicated that the photoreceptor for this response was phytochrome, an important regulator of photomorphogenesis and gene expression in plants.

NASA Discipline Plant Biology↗
NASA NTRS1976

Prospects for pipeline delivery of hydrogen as a fuel and as a chemical feedstock

The possibility of using hydrogen for storing and carrying energy obtained from nonfossil sources such as nuclear and solar energy is examined. According to the method proposed, these nonfossil raw energy sources will be used to obtain hydrogen from water by three basically distinct routes: (1) electrical generation followed by electrolysis; (2) thermochemical decomposition; and (3) direct neutron or ultraviolet irradiation of hydrogen bearing molecules. The hydrogen obtained will be transmitted in long-distance pipelines, and distributed to all energy-consuming sectors. As a fuel gas, hydrogen has many qualities similar to natural gas and with only minor modifications, it can be transmitted and distributed in the same equipment, and can be burned in the same appliances as natural gas. Hydrogen can also be used as a clean fuel (water is the only combustion product) for automobiles, fleet vehicles, and aircraft.

Gregory, D. P.↗
NASA NTRS1983

Annual Conference on Nuclear and Space Radiation Effects, Gatlinburg, TN, July 18-21, 1983, Proceedings

Topics discussed include radiation effects in devices; the basic mechanisms of radiation effects in structures and materials; radiation effects in integrated circuits; spacecraft charging and space radiation effects; hardness assurance for devices and systems; and radiation transport, energy deposition and charge collection. Papers are presented on the mechanisms of small instabilities in irradiated MOS transistors, on the radiation effects on oxynitride gate dielectrics, on the discharge characteristics of a simulated solar cell array, and on latchup in CMOS devices from heavy ions. Attention is also given to proton upsets in orbit, to the modeling of single-event upset in bipolar integrated circuits, to high-resolution studies of the electrical breakdown of soil, and to a finite-difference solution of Maxwell's equations in generalized nonorthogonal coordinates.

Source record↗
NASA NTRS2002

In vitro cell irradiation systems based on 210Po alpha source: construction and characterisation

One way of studying the risk to human health of low-level radiation exposure is to make biological experiments on living cell cultures. Two 210Po alpha-particle emitting devices, with 0.5 and 100 MBq activity, were designed and constructed to perform such experiments irradiating monolayers of cells. Estimates of dose rate at the cell surface were obtained from measurements by a PIPS alpha-particle spectrometer and from calculations by the SRIM 2000, Monte Carlo charged particle transport code. Particle fluence area distributions were measured by solid state nuclear track detectors. The design and dosimetric characterisation of the devices are discussed. c2002 Elsevier Science Ltd. All rights reserved.

Alpha Particles↗
NASA NTRS1973

Metallurgy: A compilation

A technology utilization program is presented for the dissemination of information on technological developments which have potential utility outside the aerospace and nuclear communities. Discussion is restricted to the effects of hydrogen on a variety of metal alloys, and the mechanical properties of some recently developed alloys. Hydrogen at both low and high pressure is shown to have adverse effects on alloys such as ultrahigh-strength steels, irradiated steels, columbium, inconel alloys, titanium alloys, and certain stainless steels. The mechanical and physical properties of a wide range of alloys, their performance at elevated temperatures, and some of the processes involved in their development are also considered.

Source record↗
NASA NTRS1972

Niobium hyperfine structure in crystal calcium tungstate

A study of the niobium hyperfine structure in single crystal calcium tungstate was made by the combination of the technique of electron paramagnetic resonance and electron nuclear double resonance (EPR/ENDOR). The microwave frequency was about 9.4 GHz and the radio frequency from 20MHz to 70 MHz. The rare earth ions Nd(3+), U(3+), or Tm(3+) were added as the charge compensator for Nb(5+). To create niobium paramagnetic centers, the sample was irradiated at 77 deg K with a 10 thousand curie Co-60 gamma source for 1 to 2 hours at a dose rate of 200 K rads per hour and then transferred quickly into the cavity. In a general direction of magnetic field, the spectra showed 4 sets of 10 main lines corresponding to 4 nonequivalent sites of niobium with I = 9/2. These 4 sets of lines coalesced into 2 sets of 10 in the ab-plane and into a single set of 10 along the c-axis. This symmetry suggested that the tungsten ions are substituted by the niobium ions in the crystal.

Tseng, D. L.↗
NASA NTRS2007

Testing in Support of Fission Surface Power System Qualification

The strategy for qualifying a FSP system could have a significant programmatic impact. The US has not qualified a space fission power system since launch of the SNAP-10A in 1965. This paper explores cost-effective options for obtaining data that would be needed for flight qualification of a fission system. Qualification data could be obtained from both nuclear and non-nuclear testing. The ability to perform highly realistic nonnuclear testing has advanced significantly throughout the past four decades. Instrumented thermal simulators were developed during the 1970s and 1980s to assist in the development, operation, and assessment of terrestrial fission systems. Instrumented thermal simulators optimized for assisting in the development, operation, and assessment of modern FSP systems have been under development (and utilized) since 1998. These thermal simulators enable heat from fission to be closely mimicked (axial power profile, radial power profile, temperature, heat flux, etc.) and extensive data to be taken from the core region. For transient testing, pin power during a transient is calculated based on the reactivity feedback that would occur given measured values of test article temperature and/or dimensional changes. The reactivity feedback coefficients needed for the test are either calculated or measured using cold/warm zero-power criticals. In this way non-nuclear testing can be used to provide very realistic information related to nuclear operation. Non-nuclear testing can be used at all levels, including component, subsystem, and integrated system testing. FSP fuels and materials are typically chosen to ensure very high confidence in operation at design burnups, fluences, and temperatures. However, facilities exist (e.g. ATR, HFIR) for affordably performing in-pile fuel and materials irradiations, if such testing is desired. Ex-core materials and components (such as alternator materials, control drum drives, etc.) could be irradiated in university or DOE reactors to ensure adequate radiation resistance. Facilities also exist for performing warm and cold zero-power criticals.

Houts, Mike↗
NASA NTRS1975

Materials technology for an advanced space power nuclear reactor concept: Program summary

The results of a materials technology program for a long-life (50,000 hr), high-temperature (950 C coolant outlet), lithium-cooled, nuclear space power reactor concept are reviewed and discussed. Fabrication methods and compatibility and property data were developed for candidate materials for fuel pins and, to a lesser extent, for potential control systems, reflectors, reactor vessel and piping, and other reactor structural materials. The effects of selected materials variables on fuel pin irradiation performance were determined. The most promising materials for fuel pins were found to be 85 percent dense uranium mononitride (UN) fuel clad with tungsten-lined T-111 (Ta-8W-2Hf).

Gluyas, R. E.↗
NASA NTRSDate not supplied

Affordable Development Strategy for NEP Nuclear Systems

One nuclear electric propulsion (NEP) reactor systems under consideration is a hydride moderated thermal spectrum reactor fueled by high assay low enriched uranium (HALEU). While such a reactor is expected to yield the lightest HALEU reactor design, its development challenges grow exponentially with increasing mission demands, most notably power output, specific weight of the overall system (which may require operation at temperatures exceeding 1200 K), service lifetime, and human-rated reliability. Two of the greatest cost drivers are full-powered nuclear demonstrations and extensive material development campaigns, so it is important to consider options that can minimize the need for or complexity of such tasks. This paper discusses a structured framework being developed for assessing how NEP design choices, such as materials selection, neutronic features, and heat-removal technologies, can translate into project risk and how project performance goals can be traded with development cost.Reactors operating at high temperatures often require cutting-edge heat transfer technologies and creep-resistant materials. Use of new materials in high temperature reactors brings additional complication beyond those common to any new space materials development campaign. For example, such materials may not possess necessary neutronic cross-sectional or neutronic irradiation data. Similarly, use of new materials may significantly influence core neutronics; in some extreme cases, neutronic reactivity feed-back of certain new materials can vary during their service life as radiation damage impacts the scattering cross-section. In an affordable development approach, high fidelity modeling and simulation tools are used to identify and characterize potential ‘knees-in-the-curves’ in the relationship that exists between the mission characteristics and the project risk. Of particular significance is use of modern uncertainty management and variance reduction methods to perform gap analyses that feed into phenomena identification and ranking tables (PIRT) commonly used to communicate nuclear readiness levels. Model-based measurements techniques are used to design sub-scale experiments as a substitute to minimize orcompletely eliminate the need for nuclear demonstrations.This paper will describe the approach and present preliminary results. It will lay the groundwork for developing a set of metrics that can be broadly characterized as system nuclear readiness levels and advancement degree of difficulty for nuclear systems. Equally importantly, a goal of this paper is to initiate a dialogue among stakeholders on what is the sufficient level of maturity that is required for launching a demonstration unit.

Dasari V Rao↗
NASA NTRS2017

The Beryllium-10 Abundance in an Unusual Hibonite-Perovskite Refractory Inclusion from Allende: Implications for the Origin of Be-10

Beryllium-10 (decays to B-10, t1/2 = t(sub 1/2) = 1.3 Myr) 1.3 Myr) is a radionuclide that exclusively requires a is a radionuclide that exclusively requires a spallation origin. Therefore, one could obtain important insights into the irradiation environment in the solar nebula by understanding the distribution and abundance of this radionuclide in meteoritic inclusions. Most previous data are derived from B isotopic analysis of coarse-grained CV3 Ca-Al-rich Inclusions (CAIs) that have AL-26.Al-27 Al close to the canonical level of 5 x 10 (exp -5) and inferred Be-10/Be-9 ratios between 4 x 10(exp -4) and 1 x 10 (exp -2=3) [1-5]. Al-26-depleted FUN (Fractionaed and Unknown Nuclear anomalies) CAIs are less studied due to their rarity. FUN CAIs are thought to have formed prior to homogenization of Al-26/Al-27 Al and stable isotope anomalies (e.g., Ti-50) in the solar nebula, and thus represent one of the oldest Solar System solids [6]. So far, only three FUN CAIs (Axtell 2771, KT-1 and HAL) from CV3 chondrites have been measured for Be-10. They are characterized by variable Be-10/Be-9 ratios between (2.7−4.4) × 10(exp -4) [4,7]. Another group of rare, Al-26-free and and isotopically more anomalous inclusions, namely platy hibonite crystals (PLACs) from CM2 chondrites, have well-defined Be-10/Be-9 = (5.3 +/- 1.0) x 10 (exp -4) [9]. Al-26-free CAIs appear to have lower Be-1-/Be-9 than Al-26-bearing CAIs, although large analytical errors associated with some data would allow for an apparent overlap. It has been argued that the observed Be-10 variation resulted from the in-situ production of this radionuclide in CAIs (or their precursors) by irradiation, and the ratio difference simply reflects the fluctuation in projectile fluences [e.g., 9]. Another observation in support of this explanation comes from these CAIs' initial B-10/B-11 ratios, most of which are higher than the chondritic value 0.2478 [10]. This has been interpreted as a result of mixing between spallogenic B (B-10/B-11 = 0.4, co-produced with Be-10 in the irradiated solids) and a chondritic component [5,8]. Alternatively, given that all the inferred ratios, most of which are higher than chondritic value 0.2478 [10]. This has been interpreted as a result of mixing between spallogenic B (B-10/B-11 = 0.4, co-produced with Be-10 in the irradiated solics) and a chondritic component [5,8], Alternatively, given that all the inferred ratios in CAIs never fall below 3x10(exp -4), it has been proposed that the Solar System formed with baseline Be-10/Be-9 at this level, which originated from cosmic ray irradiation of the parental molecular cloud, and any value higher than this is a result of additional in-situ spallation [4,11]. Although not explicitly stated in this model, one would expect that inclusions that incorporated the background Be-10 abundance should form with the chondritic B isotopic ratio. However, the three FUN CAIs all have supra-chondritic B-10/B-11 indicative of the presence of a spallogenic component. To test whether some Be-10 did come into the solar nebula by inheritance,a better understanding of Be-10/Be-9 and initial B-10/B-11 in Al-26-free isotopically anomalous samples is needed. Here we present the result of Be10−B-10 system in an unsual hibonite-perovskite inclusion SHAL (son of HAL) from Allende.

Liu, M-C.↗
NASA NTRS1977

Nuclear track studies of the Pasamonte and Moore County eucrites

The selective annealing technique was applied to samples from the Pasamonte eucrite with a view to obtaining fission track ages of clasts in the meteorite. The method did not permit cosmic ray tracks to be distinguished from fission tracks in either Pasamonte or Moore County. A difference between the fossil track densities observed in an igneous clast and the surrounding host material appears to be due to a pre-irradiation on the Pasamonte parent planet.

Wilkening, L. L.↗
NASA NTRS2008

The Solar Dynamics Observatory: Your Eye On The Sun

The Sun hiccups and satellites die. That is what NASA's Living With a Star Program is all about. The Solar Dynamics Observatory (SDO) is the first Space Weather Mission in LWS. SDO's main goal is to understand, driving towards a predictive capability, those solar variations that influence life on Earth and humanity's technological systems. The past decade has seen an increasing emphasis on understanding the entire Sun, from the nuclear reactions at the core to the development and loss of magnetic loops in the corona. SDO's three science investigations (HMI, AIA, and EVE) will determine how the Sun's magnetic field is generated and structured, how this stored magnetic energy is released into the heliosphere and geospace as the solar wind, energetic particles, and variations in the solar irradiance. SDO will return full-disk Dopplergrams, full-disk vector magnetograms, full-disk images at nine E/UV wavelengths, and EUV spectral irradiances, all taken at a rapid cadence. This means you can "observe the database" to study events, but we can also move forward in producing quantitative models of what the Sun is doing today. SDO is scheduled to launch in 2008 on an Atlas V rocket from the Kennedy Space Center, Cape Canaveral, Florida. The satellite will fly in a 28 degree inclined geosynchronous orbit about the longitude of New Mexico, where a dedicated Ka-band ground station will receive the 150 Mbps data flow. How SDO data will transform the study of the Sun and its affect on Space Weather studies will be discussed.

Pesnell, William Dean↗
NASA NTRS2008

The Solar Dynamics Observatory

The Solar Dynamics Observatory (SDO) is the first Space Weather Mission in NASA's Living With a Star Program. SDO's main goal is to understand, driving towards a predictive capability, those solar variations that influence life on Earth and humanity's technological systems. The past decade has seen an increasing emphasis on understanding the entire Sun, from the nuclear reactions at the core to the development and loss of magnetic loops in the corona. SDO's three science investigations (HMI, AIA, and EVE) will determine how the Sun's magnetic field is generated and structured, how this stored magnetic energy is released into the heliosphere and geospace as the solar wind, energetic particles, and variations in the solar irradiance. SDO will return full-disk Dopplergrams, full-disk vector magnetograms, full-disk images at nine EIUV wavelengths, and EUV spectral irradiances, all taken at a rapid cadence. This means you can 'observe the database' to study events, but we can also move forward in producing quantitative models of what the Sun is doing today. SDO is scheduled to launch in 2008 on an Atlas V rocket from the Kennedy Space Center, Cape Canaveral, Florida. The satellite will fly in a 28 degree inclined geosynchronous orbit about the longitude of New Mexico, where a dedicated Ka-band ground station will receive the 150 Mbps data flow. How SDO data will transform the study of the Sun and its affect on Space Weather studies will be discussed.

Pesnell, William D.↗
NASA NTRS1991

Gene activity during germination of spores of the fern, Onoclea sensibilis: RNA and protein synthesis and the role of stored mRNA

Pattern of 3H-uridine incorporation into RNA of spores of Onoclea sensibilis imbibed in complete darkness (non-germinating conditions) and induced to germinate in red light was followed by oligo-dT cellulose chromatography, gel electrophoresis coupled with fluorography and autoradiography. In dark-imbibed spores, RNA synthesis was initiated about 24 h after sowing, with most of the label accumulating in the high mol. wt. poly(A) -RNA fraction. There was no incorporation of the label into poly(A) +RNA until 48 h after sowing. In contrast, photo-induced spores began to synthesize all fractions of RNA within 12 h after sowing and by 24 h, incorporation of 3H-uridine into RNA of irradiated spores was nearly 70-fold higher than that into dark-imbibed spores. Protein synthesis, as monitored by 3H-arginine incorporation into the acid-insoluble fraction and by autoradiography, was initiated in spores within 1-2 h after sowing under both conditions. Autoradiographic experiments also showed that onset of protein synthesis in the cytoplasm of the germinating spore is independent of the transport of newly synthesized nuclear RNA. One-dimensional sodium dodecyl sulphate-polyacrylamide gel electrophoresis of 35S-methionine-labelled proteins revealed a good correspondence between proteins synthesized in a cell-free translation system directed by poly(A) +RNA of dormant spores and those synthesized in vivo by dark-imbibed and photo-induced spores. These results indicate that stored mRNAs of O. sensibilis spores are functionally competent and provide templates for the synthesis of proteins during dark-imbibition and germination.

NASA Discipline Number 29-20↗
NASA NTRS1977

Annual Conference on Nuclear and Space Radiation Effects, 14th, College of William and Mary, Williamsburg, Va., July 12-15, 1977, Proceedings

Topics related to processing and hardness assurance are considered, taking into account the radiation hardening of CMOS technologies, technological advances in the manufacture of radiation-hardened CMOS integrated circuits, CMOS hardness assurance through process controls and optimized design procedures, the application of operational amplifiers to hardened systems, a hard off-the-shelf SG1524 pulse width modulator, and the gamma-induced voltage breakdown anomaly in a Schottky diode. Basic mechanisms are examined, giving attention to chemical and structural aspects of the irradiation behavior of SiO2 films on silicon, experimental observations of the chemistry of the SiO2/Si interface, leakage current phenomena in irradiated SOS devices, the avalanche injection of holes into SiO2, the low-temperature radiation response of Al2O3 gate insulators, and neutron damage mechanisms in silicon at 10 K. Other subjects discussed are related to radiation effects in devices and circuits, space radiation effects, and aspects of simulation, energy deposition, and dosimetry.

Stahl, R. H.↗
NASA NTRS1971

Investigation of space stable thermal control coating properties

A capability to study the nuclear magnetic resonance of spacecraft thermal control coating has been built utilizing an electromagnet and V-series and Wl-series electronics. The electronics associated with the electromagnet had to be modified to make it compatible with the resonance measuring system. Resonance measurements have been performed on ZnO, Zn2TiO4 and FEP Teflon. The failure to observe resonance in ZnO and Zn2TiO4 has been theoretically explained. The linewidth and second moment measurements on ultraviolet irradiated FEP Teflon showed that there was no measurable degradation of the material due to short term irradiation.

Mookherji, T.↗
NASA NTRS1973

Effects of nuclear radiation on a high-reliability silicon power diode. 4: Analysis of reverse bias characteristics

The effects of nuclear radiation on the reverse bias electrical characteristics of one hundred silicon power diodes were investigated. On a percentage basis, the changes in reverse currents were large but, due to very low initial values, this electrical characteristic was not the limiting factor in use of these diodes. These changes were interpreted in terms of decreasing minority carrier lifetimes as related to generation-recombination currents. The magnitudes of reverse voltage breakdown were unaffected by irradiation.

Been, J. F.↗
NASA NTRS1978

Annual Conference on Nuclear and Space Radiation Effects, 15th, University of New Mexico, Albuquerque, N. Mex., July 18-21, 1978, Proceedings

Radiation effects in MOS devices and circuits are considered along with radiation effects in materials, space radiation effects and spacecraft charging, SGEMP, IEMP, EMP, fabrication of radiation-hardened devices, radiation effects in bipolar devices and circuits, simulation, energy deposition, and dosimetry. Attention is given to the rapid anneal of radiation-induced silicon-sapphire interface charge trapping, cosmic ray induced errors in MOS memory cells, a simple model for predicting radiation effects in MOS devices, the response of MNOS capacitors to ionizing radiation at 80 K, trapping effects in irradiated and avalanche-injected MOS capacitors, inelastic interactions of electrons with polystyrene, the photoelectron spectral yields generated by monochromatic soft X radiation, and electron transport in reactor materials.

Simons, M.↗